markdown-it is has a Regular Expression Denial of Service (ReDoS)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.5 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P · score source

EPSS

• CVE-2026-2327: 0.74% estimated exploitation activity in the next 30 days; percentile 54.61 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Versions of the package markdown-it from 13.0.0 and before 14.1.1 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the use of the regex /\+$/ in the linkify function. An attacker can supply a long sequence of characters followed by a non-matching character, which triggers excessive backtracking and may lead to a denial-of-service condition.

Published by the source

12 Feb 2026, 06:30 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 12:42 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-38c4-r59v-3vqw

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-38c4-r59v-3vqw

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-2327

Advisory: markdown-it is has a Regular Expression Denial of Service (ReDoS)
IDs: CVE-2026-2327, GHSA-38c4-r59v-3vqw
Record: https://patchnext.com/advisories/cve-2026-2327 (revision 3, source checked 26 Oct 2026, 12:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: markdown-it 14.1.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm markdown-it: affected >= 13.0.0, < 14.1.1; fixed in 14.1.1

## Suggested inspection (read-only)
- `npm ls markdown-it --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on markdown-it.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-38c4-r59v-3vqw (OSV record GHSA-38c4-r59v-3vqw lists affected ranges: npm markdown-it >=13.0.0 <14.1.1 (fixed))
- Verified: https://github.com/advisories/GHSA-38c4-r59v-3vqw (GitHub-reviewed advisory GHSA-38c4-r59v-3vqw lists affected ranges: npm markdown-it >=13.0.0 <14.1.1)

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